1) Field of the Invention
This invention relates to a thin film magnetic head, a magnetic head device a magnetic disk device, and a method for manufacturing a thin film magnetic head.
2) Related Art Statement
Combination type thin film magnetic heads, each having an inductive type writing element and a MR reading element, have been employed as thin film magnetic heads to constitute magnetic disk drive devices of memory devices in a computer.
Two types of longitudinal magnetic recording element and perpendicular magnetic recording element are well known as the inductive type writing element. In this specification, a thin film magnetic head having the longitudinal magnetic recording element will be called as a xe2x80x9clongitudinal recording thin film magnetic headxe2x80x9d, and a thin film magnetic head having the perpendicular magnetic recording element will be called as a xe2x80x9cperpendicularxe2x80x9d recording thin film magnetic head.
The above thin film magnetic head is mounted at the forefront of a head supporting device called as a gimbal. The head supporting device is driven by a position determining device. A rotary-actuator system is generally employed as the drive system of the position determining device. The thin film magnetic head is positioned on a given track position of a magnetic disk through the rotation drive of the position determining device for the head supporting device. The position of the thin film magnetic head on the magnetic disk is defined by a rotation angle called as a xe2x80x9cskew anglexe2x80x9d.
Generally, the position of the center line of the writing element of the thin film magnetic head tangent to the circumference of the magnetic disk is defined as skew angle zero. If the thin film magnetic head is moved toward the inside or the outside of the magnetic disk, the skew angle is increased from the zero value of the skew angle. The skew angle is normally set within 25 degrees.
The edge portion of the thin film magnetic head, which corresponds to the outflow edge of airflow when the magnetic disk is rotated, is called as a trailing edge, and the opposite edge portion to the trailing edge is called as a leading edge.
For realizing a high recording density in the magnetic disk using the thin film magnetic head, it is required that data amount (data density) to be restored in the unit area of the magnetic disk is enhanced. The surface recording density depends on the performance of the recording element of the magnetic head.
In the longitudinal recording thin film magnetic head, the surface recording density can be enhanced by reducing the gap length between the pole portions of the writing element. However, the reduction of the gap length is restricted because the magnetic flux generated in between the pole portions is decreased as the gap length is decreased.
In the longitudinal recording thin film magnetic head, if the data track number recordable in the magnetic disk is increased, the surface recording density can be enhanced. The recordable data track number is usually called as a xe2x80x9cTPI (track per inch)xe2x80x9d. The TPI performance of the writing element can be developed by reducing the size of the thin film magnetic head to define the data track width. The head size is usually defined as a xe2x80x9ctrack widthxe2x80x9d. In this specification, the track width direction will be called as a xe2x80x9ctrack directionxe2x80x9d.
An attempt is made to narrow the track width of the longitudinal recording thin film magnetic head in prior art documents. For example, Kokai Publications Kokai Hei 7-262519 and 7-225917 disclose that a first pole portion is processed by ion beam milling with a second pole portion as a mask, obtained by photolithography, so that the track width of the first pole portion can correspond to that of the second pole portion.
Kokai Publication Kokai Hei 6-28636 discloses a method for narrowing a track width as follows: After a first magnetic yoke layer (first yoke portion) is formed, a photoresist layer is formed, in which an opening is formed in order to form a magnetic pole edge assembly composed of a first pole portion, a gap film, and a second pole portion. Then, the magnetic pole edge assembly is formed in the opening, and thereafter, the part of the photoresist layer positioned at the forefront of the assembly is removed. Subsequently, a coil structure and an insulating film are formed by a conventional manner, and a second magnetic yoke layer (second yoke portion) is formed.
However, the aspect ratio (a ratio xe2x80x9ct/wxe2x80x9d of a thickness xe2x80x9ctxe2x80x9d to a width xe2x80x9cwxe2x80x9d) of the magnetic film constituting the writing pole portion is increased as the track width of the writing pole portion is narrowed. The narrowing the track width for high recording density enables the TPI to have a higher value, and thus, the distance between the adjacent tracks is set to an extremely small value of for example about 0.9 xcexcm.
If the magnetic film constituting the writing pole portion, particularly the magnetic film positioned at the trailing edge side (usually called as a xe2x80x9ctop magnetic filmxe2x80x9d) has a higher aspect ratio, the edge of the top magnetic film may be overlapped on the neighboring track in a large skew angle region. As a result, data recorded in the neighboring track may be rewritten or erased.
It is known that a perpendicular recording thin film magnetic head can have remarkably high recording density compared with the above longitudinal recording thin film magnetic head. However, if the perpendicular recording thin film magnetic head also have a higher TPI, the magnetic field generated from the side edge of the writing magnetic pole is overlapped on the neighboring track in a large skew angle region. As a result, data recorded in the neighboring track may be rewritten and erased. Herein, the wording xe2x80x9cside edgexe2x80x9d means edge portion of the writing magnetic pole in the track direction.
It is an object of the present invention to provide a thin film magnetic head, a magnetic head device and a magnetic disk drive device which can avoid magnetic harmful effects such as the above data-rewriting and data-erasing in the neighboring track.
It is another object of the present invention to provide a thin film magnetic head, a magnetic head device and a magnetic disk drive device which, in developing their TPI performances and realizing their high density recording, can avoid magnetic harmful effects such as the above data-rewriting ad data-erasing in the neighboring track.
It is still another object of the present invention to provide a method for preferably manufacturing the above thin film magnetic head.
For achieving the above objects, a thin film magnetic head according to the present invention includes a slider and at least one inductive type electromagnetic conversion element, and is driven in a radial direction of a magnetic disk at a given skew angle, as combined with the magnetic disk.
The inductive type electromagnetic conversion element includes a first magnetic film and a second magnetic film and a coil film, and is supported by the slider. One edge portion of the first magnetic film is positioned at an air bearing surface (hereinafter, called as an xe2x80x9cABSxe2x80x9d) side, and the first magnetic film is extended backward from the ABS. The second magnetic film is positioned at a trailing edge side, and one edge portion of the second magnetic film is opposed to the first magnetic film by a given distance in the ABS side. Then, the second magnetic film is extended backward from the ABS, and joined with the first magnetic film. The coil film is whirled around the magnetic circuit composed of the first and second magnetic films.
The one edge portion of the second magnetic film has at least one side surface inclined at a given inclination angle not less than the maximum skew angle in a track direction.
As mentioned above, the one edge portion of the first magnetic film is positioned at the ABS side, and the one edge portion of the second magnetic film is opposed to that of the first magnetic film via the given distance. Then, the first magnetic film is extended backward from the ABS, and the second magnetic film is extended backward from the ABS, joined to the first magnetic film. As a result, a thin film magnetic circuit having a writing pole portion in the ABS side is completed.
The coil film is whirled around the magnetic circuit composed of the first and the second magnetic films. Therefore, when a writing current is flown in the coil film, a writing magnetic flux is passed through the thin film magnetic circuit.
Since the one edge portion of the first magnetic film is positioned in the ABS side of the slider, and the one edge portion of the second magnetic film is opposed to that of the first magnetic film via the given distance, a writing magnetic field to magnetically record in the magnetic disk is generated at the gap thereof.
The second magnetic film is positioned in the trailing edge side relative to the first magnetic film, and the one edge portion thereof has at least one side surface inclined at the given inclination angle not less than the maximum skew angle in a track direction. Therefore, even though the second magnetic film has a large aspect ratio, the one edge portion of the second magnetic film can not overlap the neighboring track in a large skew angle region. As a result, the data-rewriting or the data-erasing in the neighboring track can be avoided.
The inclination of the side surface of the one edge portion of the second magnetic film depends on the recording method, that is, a longitudinal recording or a perpendicular recording of the thin film magnetic head. In the longitudinal recording thin film magnetic head, the inductive type electromagnetic conversion element includes a gap film, and thus, the one edge portions of the first and second magnetic films are opposed each other via the gap film.
In the longitudinal recording thin film magnetic head, the side surface of the one edge portion of the second magnetic film is inclined so that the track width can be decreased toward the trailing edge. Therefore, if the second magnetic film has a large aspect ratio, the one edge portion thereof can not overlap the neighboring track in a large skew angle region. As a result, the data-rewriting or the data-erasing in the neighboring track can be avoided.
In the perpendicular recording thin film magnetic head, the second magnetic film includes a main pole portion to constitute a perpendicular writing pole portion and a supplementary pole portion to magnetically join the main pole portion and the first magnetic film. The first magnetic film constitutes a magnetic flux-returning path from the main pole portion. In this case, the main pole portion has at least one inclined side surface at one edge thereof. The side surface is inclined so that the track width can be increased toward the trailing edge.
In this case, recorded data by the magnetic field generated at the side edge of the main pole portion are canceled by the magnetic field generated at the opposite edge to the trailing edge (hereinafter, called as a xe2x80x9cback edgexe2x80x9d). Therefore, magnetic recording is carried out only by the magnetic field generated at the back edge. As a result, only if the magnetic recording is carried out depart from the neighboring track by the magnetic field generated at the back edge, the magnetic field can not overlap the neighboring track in the skew region, and thus, data-rewriting and data-erasing can be inhibited even though the magnetic disk has a large TPI.
This invention will disclose a magnetic head device and a magnetic disk drive device which has the above thin film magnetic head, and a method for the thin film magnetic head.
The other objects, constructions and advantages of the present invention will be described in detail, with reference to the attached drawings in the following embodiments.